Comparing the 7mm/08 to the .308 is like comparing the .280 Remington (also a .7mm or .284 caliber) to the .30/06. Each comparision is the case of a .30 caliber cartridge necked down to .284 or 7mm.
I've always felt that for antelope, deer hunting, the .280 Remington was very
slightly superior to the .30/06 just as the 7mm/08 is very slightly superior to the .308 Winchester.
The advantage of the two 7mm cartridges compared to the two .30 caliber cartridges is the 7mm's slightly superior ballistics with slightly lighter bullets as compared to their .30 caliber "parent".
That said, I am confident that the 7mm bullets & cartridges are completely and totally appropriate for antelope or deer... and not too bad for even elk or moose, but with the larger game animals, I'd prefer the slightly heavier bullets out of the .30 caliber "parent" cartridges.
In addition to their slightly superior ballistics, especially at longer ranges... the recoil of the 7mm/08 is slightly less than the recoil of the .308 just as the recoil of the .280 Remington's (which uses a .30/06 case necked down to .284 caliber aka "7mm") recoil is slightly less than it's "parent" cartridge (the .30/06). This slightly lighter recoil is due to the fact the 7mm's are pushing slightly lighter bullets down their barrels.
The "normal" bullet weight for deer in a 7mm is usually either 120 or 140 grain bullets with the 140 grain bullet being the "more normal" compared to the .30 caliber deer bullet which is most often a 150 grain bullet although one can use a very effective 130 grain bullet as well.
And so... in summary, the 7mm cartridges will give you a slightly
flatter trajectory with almost the same bullet weight while kicking you slightly
less!
In my mind, this proves the 7mm/08 is the better choice for you than the .308 because of your eventual plans to give it to your son for his use... and at his young age, less recoil spells greater success in most cases.
Your choice in my opinion?
Get the 7mm/08 and use 120 grain bullets for your son's use... and 140 grain bullets for YOUR use. In a few years, your son should be big enough to easily handle the 140 grain, 7mm bullets as well. But I will tell you right now... the
7x57mm Mauser cartridge is a superior cartridge to the 7mm/08 if handloaded to it's maximum capability due simply to the fact the 7x57 cartridge case has a slightly
greater powder capacity than does the 7mm/08.
As a result, the 7x57 cartridge can be loaded to a slightly greater muzzle velocity which will yield a slightly flatter trajectery with slightly greater foot/pounds of bullet energy when handloaded to it's maximum capability (just as is the .308 already loaded) and fired in strong, modern rifles.
The 7x57 is normally loaded to far less pressure (46,000 CUP) as compared to the .308 Winchester (52,800 CUP) due to the use, in many 3rd world nations, of the
older &
weaker 1893 and 1895 Mausers chambered for the 7x57 cartridge which would likely give problems if loaded beyond the lower pressures the factories currently load the 7x57.
I am a handloader of long standing (over 45 years), this is why I choose my Ruger #1 International (20" barrel, full Mannlicher style stock) in 7x57 rather than 7mm/08.
Now you have the "complete story"... I hope this information will help you make your decision, but... at this point... you must certainly realize that the .308 Winchester would
also be an excellent choice.
Strength & Honor...
Ron T.
